ORGANS OF SENSE. 161 



magnified four diameters: a, b, c, d, cochlea; e-g, vestibule; h, i, 7f, pos- 

 tigfior semicircular canal ; I, m, k, superior do, ; n, o, j), horizontal do. Fig. 

 19, bony labyrinth from below, or from the side of the meatus auditorius 

 internus : a-c, base of the cochlea with the small foramina for the passage 

 of vessels and nerves ; d, foramina for the nerves of the membranous laby- 

 rinth ; e, cribriform lamina for the ampullse ; / foramen for the aqueduct 

 of the vestibule ; ^, A, ?', posterior semicircular canal ; i, k, I, superior do. ; 

 w, ji, 0, horizontal do, ; p, opening for the nerve of the posterior semicircular 

 canal ; q, aqueduct of the cochlea. Fig. 20, labyrinth magnified fouf 

 diameters to show the distribution of arteries in its interior: a, first cod of 

 the cochlea broken open ; 7;, inner surface covered by the periosteum ; f:, 

 bony portion of the lamina spiralis in the first coil ; d, vestibule ; e, canal 

 for the malleus muscle ; / g, h, artery for the labyrinth ; k^ posterior semi- 

 circular canal with its arteries; I, superior do. ; m, horizontal do. ; oi, com- 

 mon opening of the superior and posterior semicircular canal. Fig. 21, 

 general relations of the membranous labyrinth: a, cochlea; b, vestibule; 

 c-f, semicircular canals ; g, lamina spiralis ; h, edge of the lamina ; z, sinus 

 . and sacculus of the vestibule ; k, Z, Z*, ampullae of the three semicircular 

 canals ; vi, horizontal canal ; n, auditory nerve ; o, cochlear nerve ; p, j, 

 branches to the ampuUas ; r, middle branch to the sinus of the vestibule. 

 F-ig. 22, labyrinth opened : a-e, lamina spiralis ; / bony, g, cartilaginous 

 portion ; h, i, membranous portion ; I, space between the sinus and sac- 

 culus ; m, sinus with which the fine openings of the semicircular canals 

 communicate ; ??, posterior semicircular canal ; o, superior do. ; p^ hori- 

 zontal do., all with their ampullas. Fig. 23, labyrinth from beneath to 

 show the common opening of the superior and inferior semicircular canals, 

 and the course of the auditory nerve : a, cochlea ; i, vestibule ; c, d, e, pos- 

 terior semicircular canal ; / common opening ; g, horizontal canal ; e, Ä, 

 superior canal ; ^, facial nerve ; /c, auditory nerve ; Z, cochlear nerve ; w», 

 nerve for the superior and horizontal semicircular canal ; n, nerve to the 

 sinus ; o, small nerve for the ampullge of the posterior canal. Fig. 24, 

 magnified representation of the nerves of the labyrinth in the vestibule and 

 on the ampullae. Fig. 25, distribution of the cochlear nerve on the lamJHa 

 spiralis of the cochlea. Fig. 6, connected view of the different portions of 

 the ear: a, external car; b, c, meatus auditorius; d, attachment of the 

 membrana tympani; e, membrana tyrapani in its ring;/ g, h, malleus; 

 I, k, incus ; m, stapes ; w, vestibule ; p, superior ; g-, posterior ; r, horizontal 

 semicircular canals. ; 



•1. Anatomy of the Eye, or Organ of Vision. 



Ä. Appendages of the Eye not directly concerned in Vision. 



In addition to the eyeball proper, with its apparatus of lenses, fluids, and 

 membranes, in which the formation of images occurs, there are various 

 appendages all more or less concerned in protecting the eye, and in enabling 

 it to perform its functions properly and conveniently. These consist of l^e 



86V 



